1. Field of the Invention
The present invention relates generally to a magnetron plasma processing system and more particularly to a magnetron processing system having a plurality of plasma processing chambers in which rotating magnetic fields are generated.
2. Description of the Related Art
An example of a conventionally known system for subjecting semiconductor wafers or LCD substrates to an etching process or a film forming process is a so-called "cluster tool type" system wherein a plurality of processing chambers are connected to a transfer chamber. In a cluster tool type system wherein a high-density plasma for performing RIE (reactive ion etching) is generated by making use of, for example, magnetron discharge, a plurality of vacuum processing chambers are connected to a common transfer chamber in which a reduced-pressure atmosphere can be created. A pair of counter electrodes are provided within each processing chamber and a high-frequency electric field is created. A magnet mechanism is provided on top of or around each processing chamber, and a magnetic field of about 100 to 200 Gauss (G), which crosses the aforementioned electric field, is generated. Each magnetic field is rotated in order to enhance in-plane uniformity of processing on a target substrate.
In the above RIE system, however, the magnetic field in each processing chamber is disturbed due to influence of the magnetic field existing in the vicinity of each processing chamber, and consequently the density of a produced plasma varies and becomes non-uniform. In addition, noise is produced by the influence of the leak magnetic field from the system. Specifically, noise occurs in various electronic devices disposed near the system, in particular, devices having magnetic fields. For example, an image on an electronic microscope is disturbed. These problems occur not only in the RIE system, but also in other processing systems such as CVD systems or sputtering systems each having a plurality of processing chambers making use of magnetron discharge.